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The Aroma of Tea and Hang White Chrysanthemum

Author: ChaiZuo
Tutor: GuoZuoFei
School: Zhejiang University
Course: Chemistry
Keywords: Tea Water extracts contents of tea Dahongpao Hang white chrysanthemum aroma
CLC: TS222.7
Type: Master's thesis
Year: 2010
Downloads: 170
Quote: 2
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Abstract

Water extracts of tea contains a variety of biochemical components,such as tea polyphenols ,amino acids,tea caffeine,tea pigments and tea polysaccharide, The type,content and the ratio of these biochmical components are closely related to the tea quality. In other words,water extracts of tea play a decisive role in the tea quality.In this paper spectrophotometric method was used to study the content of the tea polyphenol,amino acid and tea caffeine of 23 tea samples at 30℃,60℃and 90℃,in order to find out the leaching rate of them.The leaching rate of tea polyphenols increased with the extention of brewing time and the elevation of temperature.The dissolution of the tea polyphenols was fastest in top grade tea than other samples.However,the content of tea polyphenols will reduce if maintaining along time in 90℃.The polyphenols in oolong tea,white tea and black tea dissolved slowly which required high temperature or long brewing time to get a high dissolution rate.Amino acids was easy to dissolve water,in most of the tea it was able to dissolve completely even at room temperature.The dissolution of amino acids was in concerned with the tenderness of the raw tea,however it had little relation wih the type and the processing of the tea.For the dissolution of tea caffeine,Hangshan Maofeng,oolong tea and white tea had a clear difference in 60℃and 90℃,however,caffeine content in other tea samples had little gap between the two temperatures in final time.In particular,the curve trend and the caffeine content of congou and jasmine tea were all basically the same one hour later between the two temperatures.These showed that,different raw material and processing resulted in the different rule of caffeine dissolution.Drying and baking were essential processings in traditional tea technology,however,developed in recent years the freezing tea processing eliminated the drying and baking steps.In this paper, the essential oil of baked Dahongpao and freezing Dahongpao were analyzed.Results showed that the total content did not differ much between them,but many cmponents represented great differents in the content.Pyrazine compounds and linalool were with more higher content in baked Dahongpao than in freezing Dahongpao,however a-faraesen,geraniol and nerolidol were with lower content in baked Dahongpao than in freezing Dahongpao.Phenylacetaldehyde which was with low content in other oolong teas was discovered with high content in Dahongpao.The difference in the content of the ingredients between the two samples lead to the differerce in the aroma.The aroma of the baked Dahongpao expressed densely and astringently,however the aroma of the freezing Dahongpao expressed strong,lasting and fresh tasted fragrance.Hang white chrysanthemum is a well-known drink since ancient times.Biological characteristics are distinctness of different sources cultivars,of which the main Hang white chrysanthemum produces in Tongxiang city.However,it has a great relation with the producing area,Hang white chrysanthemum was listed as original protection product in 2002,and its geographical origin is Tongxiang.In this paper,by analyzing the essential oil of Hang white chrysanthemum from four different sources to find out the characteristic aroma of Hang white chrysanthemum from Tong xiang,in order to provide a basis for the determination of the Hang white chrysanthemum original production area protection.

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